Strongest date regular expression

 

One 、 Simple date judgment （YYYY/MM/DD）： 

^\d{4}(\-|\/|\.)\d{1,2}\1\d{1,2}$

Two 、 The date of evolution （YYYY/MM/DD| YY/MM/DD）： 

  ^(^(\d{4}|\d{2})(\-|\/|\.)\d{1,2}\3\d{1,2}$)|(^\d{4} year \d{1,2} month \d{1,2} Japan $)$

3、 ... and 、 Add leap year judgment ：

example ：

            ^((((1[6-9]|[2-9]\d)\d{2})-(0?[13578]|1[02])-(0?[1-9]|[12]\d|3[01]))|(((1[6-9]|[2-9]\d)\d{2})-(0?[13456789]|1[012])-(0?[1-9]|[12]\d|30))|(((1[6-9]|[2-9]\d)\d{2})-0?2-(0?[1-9]|1\d|2[0-8]))|(((1[6-9]|[2-9]\d)(0[48]|[2468][048]|[13579][26])|((16|[2468][048]|[3579][26])00))-0?2-29-))$

analysis ：

1、 What is a legal date range ？ For different application scenarios , There are different explanations for this problem . Adopted here MSDN The agreement in ：

            DateTime Value class Type representation value Fan around In A.D. （ Christ Discipline element ） 0001 year 1 month 1 Midnight 12:00:00 A.D. (C.E.) 9999 year 12 month 31 Japan On the evening of On 11:59:59 And between Date and Time .

2、 The explanation of leap year .

      Turn off Yu Gong Calendar Leap Year is This rule Set the ： The earth Around the Sun Gong turn Once a week is called return year , Once return year Long 365 Japan 5 when 48 branch 46 second . therefore , Male Calendar rules There must be weekdays and Leap year , Every year there are 365 Japan , Bihui return Short years 0.2422 Japan , Four years is short 0.9688 Japan , so Every time Add one day in four years , this In a year 366 Japan , Just yes Leap year . But four years add one day to four returns return Years and more 0.0312 Japan ,400 There will be more 3.12 Japan , Therefore, in 400 In the middle of the year set up 3 individual Leap year , That is to say 400 Only... In the middle of the year set up 97 individual Leap year , this sample Male calendar Annual average Long And back return Years are similar . thus gauge set ： The year is a must for a hundred Must be yes 400 The multiple of is Leap year , for example 1900 year 、 2100 Years are not Leap year .

The first thing you need to verification year , display however , Year fan Surrounded by 0001 - 9999 , matching YYYY Positive of be expression by ：

[0-9]{3}[1-9]|[0-9]{2}[1-9][0-9]{1}|[0-9]{1}[1-9][0-9]{2}|[1-9][0-9]{3}

among [0-9] It can also be expressed as \d, but \d Not as good as [0-9] intuitive , So I'll always use [0-9]

There are two difficulties in using regular expressions to verify dates ： First, the number of days in big and small months is different , Second, leap year .

For the first difficulty , We don't think about leap years in the first place , hypothesis 2 Every month is 28 God , such , Month and date can be divided into three situations ：

1、 Month is 1, 3, 5, 7, 8, 10, 12, The range of days is 01 - 31, matching MM-DD The regular expression of is ：

(0[13578]|1[02])-(0[1-9]|[12][0-9]|3[01])

2、 Month is 4, 6, 9, 11, The range of days is 01-30, matching MM-DD The regular expression of is ：

(0[469]|11)-(0[1-9]|[12][0-9]|30)

3、 Month is 2, Consider the situation in ordinary years , matching MM-DD The regular expression of is ：

02-(0[1-9]|[1][0-9]|2[0-8])

According to the above results , We can get the matching year date format as YYYY-MM-DD Regular expression of ：

([0-9]{3}[1-9]|[0-9]{2}[1-9][0-9]{1}|[0-9]{1}[1-9][0-9]{2}|[1-9][0-9]{3})-(((0[13578]|1[02])-(0[1-9]|[12][0-9]|3[01]))|((0[469]|11)-(0[1-9]|[12][0-9]|30))|(02-(0[1-9]|[1][0-9]|2[0-8])))

Now let's solve the second difficulty ： Leap year considerations . According to the definition of leap year , We can divide leap years into two categories ：

1、 Can be 4 Divide but not be 100 Divisible year . Look for the change of the last two figures , You can quickly get the following regular match ：

([0-9]{2})(0[48]|[2468][048]|[13579][26])

2、 Can be 400 Divisible year . Can be 400 Divisible numbers are bound to be 100 to be divisible by , So the last two must be 00, We just need to make sure that the top two can be 4 Can be divided exactly by , The corresponding regular expression is ：

(0[48]|[2468][048]|[3579][26])00

2. Regular expression of the strongest validation date , Added leap year validation This date regular expression supports YYYY-MM-DD YYYY/MM/DD YYYY_MM_DD YYYY.MM.DD In the form of match : 2015-10-05 2015/10/05not match : 2015-10-05   2015-10-05

The complete regular expression is as follows :

((^((1[8-9]\d{2})|([2-9]\d{3}))([-\/\._])(10|12|0?[13578])([-\/\._])(3[01]|[12][0-9]|0?[1-9])$)|(^((1[8-9]\d{2})|([2-9]\d{3}))([-\/\._])(11|0?[469])([-\/\._])(30|[12][0-9]|0?[1-9])$)|(^((1[8-9]\d{2})|([2-9]\d{3}))([-\/\._])(0?2)([-\/\._])(2[0-8]|1[0-9]|0?[1-9])$)|(^([2468][048]00)([-\/\._])(0?2)([-\/\._])(29)$)|(^([3579][26]00)([-\/\._])(0?2)([-\/\._])(29)$)|(^([1][89][0][48])([-\/\._])(0?2)([-\/\._])(29)$)|(^([2-9][0-9][0][48])([-\/\._])(0?2)([-\/\._])(29)$)|(^([1][89][2468][048])([-\/\._])(0?2)([-\/\._])(29)$)|(^([2-9][0-9][2468][048])([-\/\._])(0?2)([-\/\._])(29)$)|(^([1][89][13579][26])([-\/\._])(0?2)([-\/\._])(29)$)|(^([2-9][0-9][13579][26])([-\/\._])(0?2)([-\/\._])(29)$))

Leap Year of 2 Month has 29 God , So match Leap Year date format by YYYY-MM-DD Positive of be expression by ：

(([0-9]{2})(0[48]|[2468][048]|[13579][26])|((0[48]|[2468][048]|[3579][26])00))-02-29 Last , Merge the date validation expressions of normal year and leap year , We get the final validation date format as YYYY-MM-DD The regular expression of is ：(([0-9]{3}[1-9]|[0-9]{2}[1-9][0-9]{1}|[0-9]{1}[1-9][0-9]{2}|[1-9][0-9]{3})-(((0[13578]|1[02])-(0[1-9]|[12][0-9]|3[01]))|((0[469]|11)-(0[1-9]|[12][0-9]|30))|(02-(0[1-9]|[1][0-9]|2[0-8]))))|((([0-9]{2})(0[48]|[2468][048]|[13579][26])|((0[48]|[2468][048]|[3579][26])00))-02-29)DD/MM/YYYY The regular validation expression for the format is ：(((0[1-9]|[12][0-9]|3[01])/((0[13578]|1[02]))|((0[1-9]|[12][0-9]|30)/(0[469]|11))|(0[1-9]|[1][0-9]|2[0-8])/(02))/([0-9]{3}[1-9]|[0-9]{2}[1-9][0-9]{1}|[0-9]{1}[1-9][0-9]{2}|[1-9][0-9]{3}))|(29/02/(([0-9]{2})(0[48]|[2468][048]|[13579][26])|((0[48]|[2468][048]|[3579][26])00)))